Orbit-Q: Blink LED Example

Learn how to configure your environment, set up the bootloader, and upload the classic Blink example to the STM32F405 MCU card on Orbit-Q using the Arduino IDE.

Hardware Overview & Mapping

The status LED is located directly on the STM32F405 MCU card and connected to pin PC13.

Component	Target Pin	Description
Onboard User LED	`PC13`	Green status LED on the STM32F405 MCU card
UART Bridge	`PA9` (TX) / `PA10` (RX)	CP2102 USB-C interface for flashing and serial log output

1. Arduino IDE Setup

Before writing or compiling your code, configure your toolchain options under Tools in the Arduino IDE:

Menu Item	Selected Setting	Notes
Board	`Generic STM32F4 series`	Core STM32 architecture package
Board part number	`STM32F405RGTx`	Target MCU variant (1024KB Flash, 192KB RAM)
Upload method	`STM32CubeProgrammer (Serial)`	Flashes via ROM bootloader over the CP2102 UART bridge
Port	Select CP2102 COM Port	e.g., `COMx` on Windows or `/dev/ttyUSBx` on Linux/Mac

2. Entering Bootloader Mode

To allow the STM32F405 internal bootloader to accept code over UART via the CP2102 bridge, perform the following hardware sequence:

Connect Cable: Plug a USB Type-C cable into the CP2102 USB-C port on the Orbit-Q baseboard.
Set Boot Switch: Move the Boot Slide Switch to the BOOT / ON position.
Trigger Reset: Reset the target processor using either method:
Method A: Press and release the RESET (NRST) button.
Method B: Toggle the main Power Switch OFF and back ON (or power cycle the supply rail).
Select Port: In Arduino IDE, go to Tools > Port and select the detected CP2102 serial port.

Flexibility

While this tutorial uses the CP2102 UART bridge for single-cable flashing and serial monitoring, the board also supports ST-Link V2 (SWD) and USB-OTG (DFU) upload methods.

3. Code Example

Open a new sketch in Arduino IDE or go to File > Examples > 01.Basics > Blink, then update the code as shown below:

/*
  Blink

  Turns an LED on for one second, then off for one second, repeatedly.

  On the Orbit-Q STM32F405 MCU Card by NTX Systems, the on-board status LED
  is connected to digital pin PC13. We define LED_BUILTIN as PC13 to target
  this specific pin on the hardware platform.

  modified 8 May 2014
  by Scott Fitzgerald
  modified 2 Sep 2016
  by Arturo Guadalupi
  modified 8 Sep 2016
  by Colby Newman
  modified for Orbit-Q STM32F405
  by NTX Systems Pvt. Ltd.

  This example code is in the public domain.

  https://ntxsystems.github.io/Orbit-Q/
*/

// Define the onboard LED pin for Orbit-Q STM32F405
#define LED_BUILTIN PC13

// the setup function runs once when you press reset or power the board
void setup() {
  // initialize digital pin PC13 as an output.
  pinMode(LED_BUILTIN, OUTPUT);
}

// the loop function runs over and over again forever
void loop() {
  digitalWrite(LED_BUILTIN, HIGH);   // turn the LED on (HIGH is the voltage level)
  delay(1000);                       // wait for a second
  digitalWrite(LED_BUILTIN, LOW);    // turn the LED off by making the voltage LOW
  delay(1000);                       // wait for a second
}

4. Flash and Run

Upload Sketch: Click the Upload arrow button in Arduino IDE (or press Ctrl + U).

Switch to Normal Execution: Once flashing completes, move the Boot Slide Switch back to the NORMAL / OFF position.

Execute: Press the RESET button (or power cycle the board).

Expected Output

The green status LED on your STM32F405 MCU card will turn ON for 1 second and OFF for 1 second in a continuous loop.

Troubleshooting

Upload Failed or LED Not Blinking

Failed to Init Serial Bootloader: Verify the Boot Slide Switch was set to BOOT / ON before you pressed the RESET button or power-cycled the board.
Program Doesn't Run After Upload: Ensure you toggled the Boot Slide Switch back to NORMAL / OFF and pressed RESET after uploading.
Board Not Detected: Check that the M.2 MCU card is properly seated and locked into the carrier slot.